People in the West, and particularly in California, are only too aware of earthquakes. But when very big ones fill the news, some of us in the Midwest have the recollection that we might be living over a great seismic fault of our own. That recollection is correct. The zone in question is called the New Madrid fault or seismic zone. Its name comes from the town of New Madrid, Missouri, south-east of St. Louis and almost touching Tennessee. A series of the greatest earthquakes ever took place centered around New Madrid in the years 1811 and 1812. According to the U.S. Geological Survey (USGS) these quakes damaged 600,000 square kilometers and had been perceived in a circle of 5 million square kilometers! As the USGS states here:
They were by far the largest east of the Rocky Mountains in the U.S. and Canada. The area of strong shaking associated with these shocks is two to three times as large as that of the 1964 Alaska earthquake and 10 times as large as that of the 1906 San Francisco earthquake.
The quake predated seismological measurements in the United States, hence their magnitudes are unknown. The isoseismal map of that quake, thus the intensity of it as it moved outward from its origin, is shown on the next graphic available here from the USGS. As the map shows, quite a few very large cities are in the shadow of New Madrid if that great monster should awaken, and the intensity weakens as far away from the center as Boston in Massachusetts and New Orleans in Louisiana.
Next is a photograph taken in 1912, thus a hundred years after the quake, in Lake County, Tennessee, showing stumps of trees killed by deposits of sand. The first photos taken of the damage all date from 1904 or later.
Finally, below, a USGS map of earthquake hazard regions in the United States. New Madrid is the bull’s eye there, in the center of the country.
Filed under: Disasters Tagged: | New Madrid Fault
This post should be set before every building-code committee in the Midwest. By far the biggest cause of death in Earthquakes is inadequate construction.
Interesting factoid I came across this weekend. Apparently Oregon didn’t institute seismic standards for new construction until after the Kobe, Japan, earthquake in the 1990s.
Truly astonishing given their position on the Ring of Fire!
Just as astonishing to me is the absence of any kind of Distaster Preparedness I’ve ever been told or have read about in any state or city we’ve ever lived in.
I do, however, remember those frequent drills we underwent while living on a military Post a long time ago.